JP2000290578A - Preparation of water-based pigment dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pigment composition easily dispersible in an aqueous medium in a single step without using a large quantity of water or a solvent by dry grinding a pigment containing coarse particles in the presence of a water-soluble resin, subsequently adding thereto a nonionic surfactant bearing an acetylene group and dispersing it in water. SOLUTION: A pigment containing coarse particles such as a condensed polycyclic pigment, a monoazo pigment, a disazo pigment or the like and 2-50 wt.%, preferably 10-25 wt.%, based on the pigment, of a water-soluble resin are fed to a grinding machine equipped with a built-in grinding medium such as beads or the like and subjected to dry grinding at 30-150 deg.C for 10 min to 6 hr to give a dry ground product. To this dry ground product is added 1-20 wt.%, preferably 3-10 wt.%, based on the pigment, of nonionic surfactant bearing an acetylene group and the resultant is dispersed in water. Thereby, and aqueous dispersion having equal or superior quality compared with a pigment obtained by a solvent salt milling method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Conventionally, as a method for producing an aqueous dispersion of a pigment, a pigment which has been treated so as to be suitable for an aqueous system is mixed with a dispersion varnish and then dispersed using a disperser such as a sand mill or a bead mill. The method of dispersing by spending a huge amount of energy and time was adopted. Regarding the pigment used, the pigment was finished as a product using a lot of energy and time. For example, in the pigmentation step of wet pigmentation of a crude pigment, the crude pigment is pulverized by a pulverizer such as a kneader in the presence of a pigmentation aid. Energy and time were required to separate and purify it from.

In order to solve these problems, Japanese Patent Application Laid-Open No. 55-754
No. 53 discloses a method of dry-grinding a crude phthalocyanine in the presence of a surfactant, and JP-A-9-217019 discloses a method of dry-grinding a crude pigment and then mechanically dispersing it with a resin and an organic solvent. Japanese Patent Application Laid-Open No. Hei 9-88845 proposes a method of dry-grinding crude copper phthalocyanine with a resin and an organic liquid.

[0003]

However, even with the above method, it has been insufficient to economically produce a pigment composition which can be dispersed in an aqueous medium with low mechanical energy. Therefore, the present invention provides a method for producing a pigment composition which can be easily dispersed in an aqueous medium without using a large amount of water or a solvent in a single step.

[0004]

That is, the present invention relates to a step (A) of dry-grinding a pigment containing coarse particles in the presence of a water-soluble resin, and a method of dry-grinding the pigment obtained in the step (A). ,
A process of adding a nonionic surfactant containing an acetylene group and dispersing the same in water (B).

Further, the present invention relates to the above-mentioned production method, wherein a nonionic surfactant containing an acetylene group is added in an amount of 1 to 30% by weight based on the pigment. Furthermore, the present invention relates to the above production method, wherein the water-soluble resin is an alkali-soluble resin. Furthermore, the present invention relates to an aqueous pigment dispersion obtained by the above production method.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pigments used in the present invention include condensed polycyclic pigments such as phthalocyanine pigments, quinacridone pigments and dioxazine pigments, and azo pigments such as monoazo pigments and disazo pigments. It is not limited to. The pigment to be subjected to the dry pulverization is a pigment containing coarse particles which are not preferable as a pigment in a final product form, and is preferably a condensed polycyclic crude pigment.

[0007] The water-soluble resin in the present invention is a resin commonly used as a resin component or a binder component of an aqueous pigment dispersion, or another component added to an ink concentrate using the pigment composition of the present invention. The resin may be compatible with the resin. Examples of the water-soluble resin that can be preferably used are acrylic resins such as an acrylate polymer, an acryl-styrene copolymer, and an acryl-α-methylstyrene copolymer. These acrylic resins can be dissolved in water in the presence of alkali components such as alkali metal ions, amines, and ammonia. The water-soluble resin added at the time of dry pulverization is preferably in the form of pellets because it is easy to handle.

In the present invention, the amount of the water-soluble resin to be added at the time of dry grinding is 2 to 50% by weight, preferably 10 to 25% by weight, based on the weight of the pigment. The resin ratio in the concentrate using the pigment composition is increased, the use of the aqueous dispersion is limited, or it is not preferable because it cannot be used, and the pigment composition obtained by dry pulverization when the amount is less than the above value is dissolved in water. It is not preferable because peptization becomes difficult.

The nonionic surfactant containing an acetylene group of the present invention is an aliphatic compound having an acetylene group and a hydroxyl group in the molecule, and specifically, 2,4,7,9-tetramethyl-5.
-Desine-4,7-diol or an ethylene oxide adduct thereof. A mixture of a nonionic surfactant containing an acetylene group, ether and glycol is preferable in use.

In the present invention, the amount of the nonionic surfactant containing an acetylene group used in the step of dispersing the dry pulverized product in water is 1 to 20% by weight, preferably 3 to 10% by weight based on the pigment. In addition, when the amount of the surfactant is larger than the above, the use of the aqueous pigment dispersion is limited. Also,
When the amount of the surfactant is small, the pigment composition does not peptize in the vehicle, and the pigment does not develop color, particularly when a phthalocyanine pigment is used. Another surfactant may be used in combination with the nonionic surfactant containing an acetylene group.

In the dry pulverization of the present invention, a pulverized material is pulverized in a powder state without using a pulverizer incorporating a pulverization medium such as beads or the like, without agglomerating the pigment with water or a solvent. Examples of the pulverizer include a dry attritor, a ball mill, a vibration mill and the like, but an attritor is preferable in terms of production efficiency.

The conditions for dry pulverization must be set according to the equipment to be used, but the pulverization temperature is preferably from 30 to 150 ° C. In particular, when the pulverization temperature is higher than the softening point of the water-soluble resin to be used, there is a high risk that the pulverized material will adhere to the inside of the dry apparatus. Therefore, it is necessary to set as low as possible the softening point of the water-soluble resin used. The pulverization time is preferably from 10 minutes to 6 hours, and if the pulverization time is short, it is not preferable because the pigment contains particles that are not sufficiently pulverized.
If the pulverization time is long, the production efficiency deteriorates, which is not preferable.

The pigment composition of the present invention is in a state where the surface of a finely pulverized pigment is covered with a resin, and is easily peptized and dispersed in water in the presence of an alkali. The pigment composition of the present invention can be made into an aqueous pigment dispersion by a simple operation such as stirring and mixing with an aqueous pigment dispersion vehicle in the presence of an alkali.

The pigment-dispersed particles contained in the pigment composition obtained by the present invention can have substantially the same particle diameter as the pigment particles obtained by the solvent salt milling method. The aqueous pigment dispersion of the present invention can be used, for example, as an aqueous paint, a printing agent, an aqueous ink, an ink for ink jet, a dispersion for a color filter, and the like.

[0015]

The present invention will be specifically described below with reference to examples and comparative examples. The pigment used as a standard pigment in the examples was obtained by converting a crude pigment into a pigment by solvent salt milling, and an X-ray diffractometer was used to measure the crystal form. The particle size and particle morphology were observed with a transmission electron microscope.

[0016]

Example 1 Crude copper phthalocyanine was added to a dry attritor.
84 parts by weight and 16 parts by weight of an acrylic resin ("Johncryl J-679" manufactured by Johnson Polymer) were added and pulverized at 90 ° C for 20 minutes. The content of α-type crystals in the obtained pigment composition is 50.
%. Next, 18 parts by weight of the obtained pigment composition was combined with 1.0 part by weight of a nonionic surfactant containing an acetylene group (“Olfin STG” manufactured by Nissin Chemical Industry Co., Ltd.) together with sodium hydroxide for dissolving the resin. The concentrated dispersion was obtained by adding 20 parts by weight of the aqueous solution containing the mixture and gently stirring at room temperature. Next, after adding 61 parts by weight of an aqueous styrene acrylic emulsion to the obtained concentrated dispersion and adjusting it to a final ink, and comparing with a standard ink containing the same pigment, the ink of this example showed coloring power and transparency. It was superior to the standard ink in terms of sharpness and the like, and had a tinting strength of about 140%. The average dispersed particle size at this time is 80 to 120 nm
Met.

[0017]

Example 2 Crude copper phthalocyanine was added to a dry attritor.
84 parts by weight and 16 parts by weight of an acrylic resin ("Johncryl J-679" manufactured by Johnson Polymer) were added and pulverized at 90 ° C for 20 minutes. Α-type crystal content of the obtained pigment composition is 50%
It was about. Next, 18 parts by weight of the obtained pigment composition was combined with 1.0 part by weight of a nonionic surfactant containing an acetylene group (“Surfinol TG” manufactured by Nissin Chemical Industry Co., Ltd.) together with sodium hydroxide for dissolving the resin. Was added to an aqueous solution containing 20 parts by weight, and the mixture was stirred gently at room temperature to obtain a concentrated dispersion. Next, after adding 61 parts by weight of an aqueous styrene acrylic emulsion to the obtained concentrated dispersion and adjusting it to a final ink, and comparing with a standard ink containing the same pigment, the ink of this example showed coloring power and transparency. It was superior to the standard ink in terms of sharpness and the like, and had a tinting strength of about 130%. At this time, the average dispersed particle size was 80 to 120 nm.

[0018]

Example 3 Crude copper phthalocyanine was added to a dry attritor.
84 parts by weight and 16 parts by weight of an acrylic resin (Johncryl J-679 manufactured by Johnson Polymer) were added and pulverized at 90 ° C. for 20 minutes. Α-type crystal content of the obtained pigment composition is 50%
It was about. Next, 18 parts by weight of the obtained pigment composition was added together with 1.0 part by weight of a nonionic surfactant containing an acetylene group (“Surfinol 504” manufactured by Nissin Chemical Industry Co., Ltd.) together with sodium hydroxide for dissolving the resin. Was added to 20 parts by weight of an aqueous solution containing, and the mixture was stirred gently at room temperature to obtain a concentrated dispersion. After adding 61 parts by weight of an aqueous styrene acrylic emulsion to the obtained concentrated dispersion and adjusting it to a final ink, and comparing with a standard ink containing the same pigment, the ink of this example showed tinctorial strength, transparency, and sharpness. It was superior to the standard inks in terms of color and the like, and had a coloring power of about 110%. The average particle size at this time was 80 to 120 nm.

[0019]

Comparative Example 1 Crude copper phthalocyanine was added to a dry attritor.
84 parts by weight and 16 parts by weight of an acrylic resin ("Johncryl J-679" manufactured by Johnson Polymer) were added and pulverized at 90 ° C for 20 minutes. Α-type crystal content of the obtained pigment composition is 50%
It was about. Next, 18 parts by weight of the obtained pigment composition was added to an aqueous solution 20 containing sodium hydroxide for dissolving the resin.
A concentrated dispersion was obtained by gently stirring at room temperature in addition to the parts by weight. Next, 62 parts by weight of an aqueous styrene acrylic emulsion was added to the resulting concentrated dispersion to prepare a final ink, but almost no color was formed.

[0020]

Comparative Example 2 Crude copper phthalocyanine was ground at 90 ° C. for 20 minutes using a dry attritor. The α-type crystal content of the obtained pigment was about 30%. Next, 15 parts by weight of the obtained pigment was combined with 1.0 part by weight of a nonionic surfactant containing an acetylene group (“Olfin STG” manufactured by Nissin Chemical Industry Co., Ltd.) and water 20
A concentrated dispersion was obtained by gently stirring at room temperature in addition to the parts by weight. Next, 64 parts by weight of an aqueous styrene acrylic emulsion was added to the obtained concentrated dispersion to prepare a final ink, but almost no color was formed.

[0021]

Example 4 Crude copper phthalocyanine was added to a dry attritor.
84 parts by weight and 16 parts by weight of an acrylic resin ("Johncryl J-679" manufactured by Johnson Polymer) were added and pulverized at 90 ° C for 20 minutes. The content of α-type crystals in the obtained pigment composition is
It was about 50%. Next, 18 parts by weight of the obtained pigment composition was added to 0.5 parts by weight of a nonionic surfactant containing an acetylene group (“Olfin STG” manufactured by Nissin Chemical Industry Co., Ltd.) together with sodium hydroxide for dissolving the resin. Was added to an aqueous solution containing 20.5 parts by weight, and the mixture was stirred gently at room temperature to obtain a concentrated dispersion. Next, after adding 61 parts by weight of an aqueous styrene acrylic emulsion to the obtained concentrated dispersion and adjusting it to a final ink, and comparing with a standard ink containing the same pigment, the ink of this example showed coloring power and transparency. Superior to standard inks in clarity, etc., and coloring power is 120%
It had a good grade. The average dispersed particle size at this time was 80
120120 nm.

[0022]

Example 5 Crude copper phthalocyanine was added to a dry attritor.
84 parts by weight and 16 parts by weight of an acrylic resin ("Johncryl J-679" manufactured by Johnson Polymer) were added and pulverized at 90 ° C for 20 minutes. The content of α-type crystals in the obtained pigment composition is 50.
%. Next, 18 parts by weight of the obtained pigment composition was combined with 2.0 parts by weight of a nonionic surfactant containing an acetylene group (“Olfin STG” manufactured by Nissin Chemical Industry Co., Ltd.) together with sodium hydroxide for dissolving the resin. A concentrated dispersion was obtained by adding 19 parts by weight of the aqueous solution containing the solution and gently stirring at room temperature. Next, after adding 61 parts by weight of an aqueous styrene acrylic emulsion to the obtained concentrated dispersion and adjusting it to a final ink, and comparing with a standard ink containing the same pigment, the ink of this example showed coloring power and transparency. It was superior to the standard ink in terms of sharpness and the like, and had a tinting strength of about 150%. The average dispersed particle size at this time is 80 to 120 nm.
Met.

[0023]

The pigment obtained according to the present invention has the same or better quality as the pigment obtained by the solvent salt milling method used as a general pigment production method, and has a lower cost. To provide the pigment. The pigment composition of the present invention can disperse a pigment in water by a simple operation.

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[Procedure amendment]

[Submission date] March 13, 2000 (200.3.1)
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

[0001] The present invention relates to an aqueous medium having a low concentration.
Aqueous pigments that can be dispersed with mechanical energy
The present invention relates to a method for manufacturing powder.

2. Description of the Related Art Conventionally, as a method for producing an aqueous dispersion of a pigment, a pigment which has been treated so as to be suitable for an aqueous system is mixed with a dispersion varnish, and then a huge amount of the pigment is dispersed using a disperser such as a sand mill or a bead mill. The method of dispersing by spending energy and time was adopted. Regarding the pigment used, the pigment was finished as a product using a lot of energy and time. For example, in the pigmentation step of wet pigmentation of a crude pigment, the crude pigment is pulverized by a pulverizer such as a kneader in the presence of a pigmentation aid. Energy and time were required to separate and purify it from.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

That is, the present invention relates to a step (A) of dry-grinding a pigment containing coarse particles in the presence of a water-soluble resin, and a method of dry-grinding the pigment obtained in the step (A). ,
The nonionic surfactant containing an acetylene group added process for producing water-based pigment fraction <br/> Chikarada consisting the dispersion allowed to step (B) in water.

Claims (4)

[Claims] 1. A step (A) in which a pigment containing coarse particles is dry-pulverized in the presence of a water-soluble resin, and a nonionic surfactant containing an acetylene group is added to the dry-pulverized product obtained in the step (A). (B) adding an agent and dispersing in water. 2. The method according to claim 1, wherein the nonionic surfactant having an acetylene group is added in an amount of 1 to 30% by weight based on the weight of the pigment. 3. The method according to claim 1, wherein the water-soluble resin is an alkali-soluble resin. 4. An aqueous pigment dispersion obtained by the production method according to claim 1.